Thermoplastic blends of polyamide with polymers containing ester or carbonate linkages are well known. Particularly, polycarbonates have been blended with polyamides to produce blends having various modified properties. Japanese Kokai No. 116541/50 discloses blends of 5-20% by weight nylon 12 and 80-90% by weight polycarbonate for use in electric insulators. Japanese Pat. Kokai No. 85420/56 discloses polyamide fibers containing 0.5%-10% by weight polycarbonate. Japanese Pat. Publn. No. 26936/76 discloses adhesive compositions containing 5-40% by weight of polycarbonate resin and 95-60% by weight polyamide resin. Japanese Pat. Kokai No. 61050/55 discloses molding compositions containing 100 weight parts poly(ester-carbonate) and 1-150 weight parts polyamide. U.S. Pat. No. 4,317,891, Sakano, et al., discloses thermoplastic blends containing polycarbonate, polyamide, and conjugated diene rubber copolymer.
Polyamide blends with polyester are also known. Japanese Pat. Kokai No. 54657/51 discloses blends of poly(ethylene-terephthalate) with polyamide. Japanese Pat. Kokai No. 113049/59 discloses blends of a polyarylate, polycarbonate, and polyamide. Japanese Pat. Kokai No. 50,061/55 discloses blends of poly(ester-carbonate) and polyamide. U.S. Pat. No. 3,989,655 discloses blends of polyester and polyamide.
The above disclosed blends are useful for their intended purpose. However, it is well known that such blends by no means live up to expectations in either the combination of physical properties present or the level of physical properties attained. Impact strength is poor. The viscosity and molecular weight of the blends is at less than expected levels. It is theorized that these blends lack the degree of chemical compatibility necessary for each resin to contribute the excellent physical properties that it may possess to the blend as a whole.
Thus, it is an object of the present invention to produce blends of polyamide with a polymer containing ester or carbonate linkages having improved impact strength, viscosity retention and molecular weight retention. It is another object of the present invention to produce blends of polyamide with a polymer containing ester or carbonate linkages having improved chemical compatibility.